湍流对旋流器分离和分级的影响

根据旋流器的流场理论,分析了旋流器内湍流运动对物料分离效率和分级精度的影响,介绍了降低湍流强度的一些方法。     

溢流管直径对旋流器流场和分离影响研究

利用RSM雷诺应力模型和VOF多相流模型,系统考察了溢流管直径对Φ50 mm水力旋流器流场稳定性的影响。通过对空气柱、零速包络面、短路流及湍流强度等流场特性的分析,确定了使流场稳定的最佳溢流管直径范围,并通过旋流分离物理试验进一步验证了该溢流管直径条件下获得的稳定流场能有效提高分离效率。研究结果表明,当溢流管直径过小时,空气柱会发生中断甚至不能完整形成,分选空间内部湍流强度较高,底流分流比较大,短路流量较小。随着溢流管直径的增加,逐渐形成上下贯通的空气柱,分选空间内部湍流强度降低,零速包络面的对称性增强,底流分流比逐渐降低,流场稳定性增强,从而分离性能增强。随着溢流管直径进一步增加,空气柱直径增大,短路流量增加,流场稳定性降低,从而分离效率下降。因此,针对所考察的Φ50 mm水力旋流器最佳的溢流管直径在0.30 D左右。     

矿浆粘度对水力旋流器分级的影响

在一套装有线粘度计的水力旋流器试验系统中进行了矿浆粘度对水力旋流器分级的影响的试验。这套系统利用了一台振动球形粘度计和专门设计的矿浆显示装置，以避免粘度测量过程中出现固体颗粒沉淀的现象。试验矿浆样品为磨细的石英砂和水的混合物。样品的固体含量和温度可以变化，以便改变矿浆的粘度。用改型的Ｐｌｉｔｔ模型来预测ｄ５０（ｃ）的粒度大小。原模型的粘度粘度仅由固体的含量来推断，但改型后的模型输入了粘度参数，可对     

旋流器安装倾角和部分参数对分级指标的影响

对旋流器沉砂口的磨损，旋流器的安装倾角及给矿压力对分级指标的影响进行了系统试验，建立了相应的数学模型，解决了当沉砂口磨损后通过调节安装倾角和给矿压力保持旋流器分级指标不变的计算问题，为旋流器运行控制提供了理论依据。     

锥角对水力旋流器流场及分离性能影响的数值试验研究

为了考察锥角对水力旋流器内部流场和分离性能的影响，针对实验室[?]50 mm水力旋流器，采用Fluent软件中RSM湍流模型、VOF和Mixture多相流模型进行了系统的数值试验研究。流场模拟结果表明，在相同操作条件下，增大锥角，空气柱直径增大，湍流强度增加，压强和压强梯度均明显增加，从而导致整体能耗增加；切向速度随锥角增大明显升高，轴向速度变化不大，但LZVV逐渐向器壁移动，分流比逐渐降低。颗粒分离模拟结果表明，增大锥角会导致分离粒度增加，各粒级分离效率降低；小锥角容易造成“底流夹细”现象，大锥角容易引起“溢流跑粗”现象。研究结果为水力旋流器锥体的结构选择和设计提供了参考。     

多粒级分级旋流器的初步研制

研制成多粒级分级旋流器。该设备结构独特,旋转流场具有准强制涡特性,其三维速度分布与普通旋流器速度场不同,但压力分布规律一致。试验表明,该设备有满意的多粒级分级功能,且分级效果良好。     

柱锥连接处扩径对水力旋流器性能的影响

研究了柱锥连接处适度扩径对水力旋流器性能的影响。在其它条件相同的条件下, 对扩径后锥角为20°和30°水力旋流器的分级效率、分级精度、处理能力、分流比和浓缩性能等进行了对比试验。试验结果表明, 相对于普通水力旋流器, 柱锥连接处适度扩径的水力旋流器分级效率总体上提高了, 但浓缩效果变差, 处理能力减小, 而且随着扩径幅度的增加而减小; 分流比随扩径幅度增大而增大。所得研究成果对选择旋流器结构参数以满足不同条件要求具有指导意义。     

水力旋流器的结构参数对凡口铅锌矿分级性能的影响

以自制的水力旋流器对广东凡口铅锌矿进行了分级试验, 考察了旋流器沉砂口直径、溢流口直径和溢流管插入深度等结构参数对分级粒度的影响, 确定了最佳结构参数。用拉苏莫夫法对试验结果进行了分级粒度的分配计算,并将实际分级粒度与最大切向速度轨迹面法计算的理论值进行了对比分析, 发现两者存在一定的偏差, 表明拉苏莫夫法需要进行一定程度的修正之后才能适用于凡口铅锌矿。     

改进旋流器结构提高分级效率的研究

本文介绍了一种新型ＧＴＺ旋流器，这种旋流器消除或减小了空气柱对分极过程的不利影响，显著提高了旋流器的分极效率，为旋流器的应用开辟了新途径。     

平底结构对水力旋流器流场特性及分离性能影响

基于数值模拟对比了渐缩平底旋流器与复合锥角旋流器流场特性,探究平底结构对水力旋流器流场的影响。结果表明,两种水力旋流器压强分布和切向速度分布基本一致,而空气柱附近压强梯度存在差异;渐缩平底旋流器溢流管下方湍流强度较低而底流口附近则相反;渐缩平底旋流器柱-锥交界面的空气柱附近轴向速度较高,导致其分流比较低。实验室旋流分离试验结果表明,平底结构能有效抑制溢流跑粗和底流夹细现象,显著提高分级效率,改善水力旋流器分离性能。     

动态水力旋流器流场数值模拟研究

动态水力旋流器具有分离效率高、压力损失小、处理量及处理量变化范围大等优点,是近年来研究比较多的除尘和油水分离设备.本文基于计算流体力学原理,利用流体力学FLUENT对中心进料式动态水力旋流器内部流场进行了研究和分析.通过模拟,可以准确地反映流场内部情况,从而对动态水力旋流器的分离效果及其性能进行预测并指导设计旋流器结构,为动态水力旋流器的优化设计提供依据.     

三锥角水介旋流器锥体结构优化及数值模拟

为了考察三锥角水介旋流器的锥体分选特点,采用正交试验和计算流体力学的方法,对三锥角水介旋流器的锥体结构进行初步研究。首先通过正交试验探究不同角度锥体对粗煤泥分选效果的影响,在满足最大产率原则的条件下,得到较优的锥体参数。然后利用ICEM-CFD对三锥角水介旋流器的内部流场进行数值模拟,湍流相采用雷诺应力RSM模型,采用DPM离散相模型模拟三锥水介旋流器内颗粒运动,分析内部流场的压力、速度分布规律及固体颗粒运动轨迹,结果表明：三段锥体对分选效果都有影响,影响程度为一段锥体＞二段锥体＞三段锥体|一段锥体能够获得较低的精煤灰分,二段和三段锥体能在要求的灰分范围内保证较高的精煤产率。     

具有中心插入物结构水力旋流器流场特性及分离性能的研究

使用计算流体力学软件FLUENT15.0对中心棒及辅助构件中心粗棒、中心锥和中心渐扩导管这四种中心插入物结构水力旋流器进行了数值模拟,分析了添加中心插入物结构对传统水力旋流器内流场的影响,对中心插入物结构以及传统水力旋流器的分级效率进行了比较。模拟结果表明:与传统水力旋流器相比,添加中心插入物结构能够提高旋流器内流场的稳定性并降低产品粒度粗细混杂程度。模拟结构也为进一步优化中心插入物结构提供了参考。     

New understanding of a hydrocyclone flow field and separation mechanism from computational fluid dynamics

The flow field of a 2 in. hydrocyclone is shown to be significantly asymmetric without precession, through both computational fluid dynamics (CFD) and experimental observation. Hence the application of full three-dimensional modelling is demonstrated to be essential. Further, CFD predicts that the axial pressure is not below atmospheric prior to development of the air core and that such development is not pressure driven. In fact, initial insight into a cause of instability of the air-core is identified from the CFD and supported through experimental observation. The predictions use the second-order differential-stress turbulence model which has previously been identified to represent a minimum model. Lastly, the inclusion of full three-dimensional modelling and high-order turbulence modelling leads to a new understanding of particle-separation classification within the hydrocyclone, including a significant stochastic component.     

进料压力及含固量对铀矿浆分级性能的影响

通过对水力旋流器进行各项物料分配比及分级效率的试验,探讨进料压力及矿浆中固体质量分数对水力旋流器分级性能的影响。试验结果表明,进料压力为0.08~0.10MPa、进料矿浆中固体质量分数13%时,水利旋流器的分级效率稳定,分级效果可满足工艺要求。     

Hydraulic and sediment removal performance of a modified hydrocyclone

Traditionally, settling basins have been used to exclude suspended sediment in hydropower plants. However, due to the inability of such basins to exclude fine sediment (predominantly hard minerals such as quartz and feldspar) and the excessive sediment loads in Himalayan Rivers, hydro-mechanical equipment and accessories in these plants have been severely damaged. Not only does this involve huge maintenance costs, but there is also a substantial revenue loss due to reduced equipment efficiencies. Thus, more efficient devices such as hydrocyclones are required to remove sediment particles. However, the geometry of a hydrocyclone plays an important role in hydraulic and sediment removal efficiency, and this paper analyses the experimental results of a test rig consisting of a hydrocyclone, 0.38 m in diameter, with a modified geometry. The results were compared with those of other investigators, and show that the modified hydrocyclone gives better hydraulic and sediment removal. The implications for suspended sediment exclusion in hydropower plants of Himalayan region are pointed out.     

液压圆锥破碎机的结构和工艺性能研究

简述了当代液压圆锥破碎机的结构和演变历史,讨论了主要参数对破碎工艺性能的影响.以鞍钢齐大山硬度大、难破碎矿石应用为例,计算了HP800和H8800在中细碎作业中的生产能力,并发现HP800无论是作中碎还是作细碎使用,在生产合格产品的能力等工艺性能方面均比H8800优越.     

Performance of a deoiling hydrocyclone during variable flow rates

Hydrocyclones are state of the art technology for treating produced water offshore. In the acceleration field inside the hydrocyclone oil migrates to the cyclone centre as water is forced to the wall. Separation is depending on the characteristic two-fold vortex flow structure featuring hydrocyclones. Deoiling hydrocyclones do not always meet water quality requirements, however. This paper, describes experimental investigations and hydrocyclone efficiency during transient flow rates. A laboratory test rig exposed a hydrocyclone to severe transient flow rates. Efficiency disturbances may be detected by increased oil-in-underflow, which again is associated with vortex disturbances and plausible vortex breakdown. Experiments led to no such dramatic disturbances. However, separation effects traceable to a limited influence on the flow split were realized. This investigation emphasizes the importance of adequate hydrocyclone operational control. Based on experimental results it is concluded that hydrocyclone efficiency is unaffected by transient flow rates provided the hydrocyclone performance criteria are fulfilled.     

Using a high pressure hydrocyclone for solids classification in the submicron range

A 10 mm hydrocyclone was operated using a barite suspension with a maximum particle size of d^max = 7 μm. The test rig was equipped with a piston diaphragm pump for pressures up to 60 bar. At 40 bar and 20 °C, cut sizes d₅₀ were obtained down to 0.7 μm; increasing the temperature to 50 °C resulted in d₅₀ values down to 0.5 μm for a throughput of 0.6 m³/h. Another experiment was conducted at 40 bar using a batch hydrocyclone technology. Only the overflow was recirculated to the feed box, whereas the underflow was discharged via a collection box. Increasing the number of recirculations increased the separation of fines in the submicron range. The results showed that after 20 min particles with d^max = 1 μm were obtained in the hydrocyclone overflow. After 120 min, the particles size distribution had a d^max = 0.5 μm and a mean size of d⁵⁰ = 0.2 μm. This procedure requires high energy consumption and is thus suitable only for fractionating small quantities of particles in the submicron range.